Talking-machine modulator



May 27, 1924. 1,495,266

C. SCRABIC TALKING MACHINE MODULATOR Filed April 28 1920 Patented May 27, 1924.

CARL SCRABIC, 0F URBANA, OHIO.

TALKING-MACHINE MODULATOR.

Application filed April 28, 1920.

To all whom it may concern:

Be it known that CARL SCRABIO, a citizen of the United States, residing at Urbana, in the county of Champaign and State of Ohio, has invented certain new and useful Improvements in Talking-Machine Modulators, of which the following is a specification.

This invention relates broadly to talking machines and has particular reference to an improved structure for regulating the intensity or volume of the sounds emitted from the amplifier structures of such machines.

The primary object of the invention resides in the provision of a tone modulator of the aforesaid character wherein is embodied a pair of pivotally movable jaws which arev relatively disposed in such manner that the same may be moved to increase or decrease the diameter of that portion of the amplifier structure in which the modulator is mounted, the construction being such that the modulator will simply tend, when substantially closed, to soften the tonal qualities of the sound vibrations without in any way sacrificing their real values. In other words, the modulator comprising the present invention is constructed with the view of not merely muffiing sounds-within an amplifier, as is common in past constructions, but with the view of merely lessening the sound intensity and at the same time preserving over-tones and partials.

For a further understanding of the invention, reference is to be had to the following description and to the accom-- panying drawing, in which similar characters of reference denote like and corresponding parts.

In said drawing:

Figure 1 is a transverse vertical sectional View taken through the amplifier structure of a talking machine and disclosing the location and construction of the modulator forming the subject matter of the present invention.

Figure 2 is a similar view disclosing the jaws of the modulator in a position partially obstructing the amplifier.

Figure 3 is a similar view disclosing the jaws in their fully closed position, and,

Figure 4 is a vertical longitudinal sectional view taken through the amplifier and the cooperative modulator.

In the form of the invention disclosed in Serial No. 377,220.

the accompanying drawing, a talking machine cabinet 1 1S employed which is formed to embody an amplifier or sound conduit 2,

which latter is adapted for connection with.

the usual sound reproducing elements, not shown, for the purpose of enlarging and enhancing the sound vibrations set up within said reproducing mechanism. It is'desirable that the sounds passing through the conduit 2 may be controlled in such manner as to render a talking machine adaptable to different musical compositions and to the size of the room or auditorium in which the machine is in use. To this end many talking machines of the prior art have been equipped with modulating devices especially adapted for this purpose, however, such past devices are believed to be open to the objection that the same merely tend to mufile sounds passing through the amplifier, and that by so muilling such sounds, their fine tonal properties and shadings are to a Very great extent lost and the expressionlof the sounds accordingly destroyed. Therefore, the present invention aims to produce a modulator wherein the sounds passingthrough the amplifier may be reduced in intensity and volume without losing the fine partials and over-tones which are so thoroughly essential in musical sound reproduction.

This object is mainly accomplished byithe provision of a modulator 3 which consists of a pair of pivotally movable jaws or members 4; and 5. As shown, these jaws are of substantially semi-circular formation and are pivotally connected at one side to the pin 6 and are formed to terminate in offset crank extremities 7. These extremities are connected by means of links 8 to a common actuating rod 9, which latter is slidably mounted within the walls of the cabinet 1. Manifestly, by sliding the rod 9, the aws 4 and 5 may be oscillated relatively about the pin 6 so as to assume various positions of sound regulation. Normally, when the jaws are separated, the same will be so positioned, see Figure 1, as to be sub stantially independent of the sound conduit 2, thus permitting of the free passage of sound waves through the amplifier without encountering obstructing influences.

However, as shown in Figures 2 and 3, by

moving the plunger or rod 9 outwardly, the

jaws 4' and 5 will be moved together in such manner that the jaws will obstruct or par tially obstruct the conduit 2. However, ow-

ing to the formation of the jaws, it will be obvious that such relative movement thereof will simply result in decreasing the diameter of that portion of the amplifier in which they are situated. In other words, the amplifier is not obstructed by the damper valves of past formation, but simply has its effective diameter so reduced that the desired softening of the tones may be obtained withoutunduly muffiing or dividing the flow or passage of the sound waves.

Preferably, the jaws 4t and 5 are formed from wood and frequently the presence of this material will prevent undue metallic notes from being set up by the modulator. Again, as shown in Figure 3, the jaws may be completely closed so as to obstruct the conduit 2, but since said jaws are formed of a resonant material, sound vibrations of a soft and pleasing character will still be emitted by the mouth of the amplifier. In other words, when in the position shown in Figure 3, the jaws l and 5 will constitute a resonant body or diaphragm which will be capable of vibrating synchronously with the sound waves set up by the reproducing mechanism and will therefore be capable of transmitting such waves to the outlet side of the amplifier. It will be noted that by the construction of the jaws and 5, the diameter of the conduit 2 is capable ofbeing minutely regulated in order that any desired adjustment of sound transmission within the cabinet 1 may be obtained.

Preferably the jaws t and 5 arelocated within cooperating recesses 10 formed in adjacent faces of a pair of easing members 11, also formed of wood. These members are positioned between certain of the horizontal walls of the cabinet 1 and are provided with axial openings 12 inwhich the ends of the amplifier sections 18 and 14 are situated. Therefore, the casing members 11 will serve to support both the sections 13 and 14 and will retain the jaws 4 and 5 in cooperative relation with respect thereto, the pin 6 being connected with thecasing members in such manner as to retain the jaws in cooperative relation with the sound passages formed in sections 13 and 14.

Any suitable mechanism may be employed for effecting the manual operation of the rod 9. In this instance, said rod has been shown as provided with a fixed collar 15 against which one; end of a coiled spring 16 presses. The opposite end of this spring engages with a fixed bracket 17 carried by one of the vertical walls of the cabinet 1. The arrangement ofthe spring is such that it will normally tend to retain the jaws 4 and 5 in their separate positions, thus permitting of the free and unrestricted passage of sound waves through the conduit 2. Therefore,

adjustment of the jaws may be obtained by providing the outer end of the plunger or rod with a manipulating knob 18, which cooperatively carries spring pressed dogs 19, the latter being adapted for engagement with any one of a plurality of notches 20 formed in an escutcheon plate 21, the latter being rigidly mounted upon one of the outer walls of the cabinet. Manifestly, by moving the rod 9 through the provision of the knob 18, said rod may be retained in a plurality of slidably adjusted positions, thus controllingthe operative positions of the jaws 4: and 5. The plate 21 may be provided with graduations 22 by means of which the positions of the jaws 4c and 5 may be visually determined.

Through the provision of the structure de-.

scribed, the tones of a talking machine may be moved to suit the taste of an auditor by merely moving the plunger 9, this will result in opening or closing the sound conduit so as to obtain loud and full tones, intermediate or soft and low tones, the adjustment operating .to obtain the desired tonal shades or interpretation of the record being conduit for regulating the passage of sound therethrough, said structure comprising a pair of sound controlling members arranged in overlapping relation and mounted for movement relative to said conduit so as to open or close the latter for sound passage, said members being provided with recesses in contiguous edge portions thereof, whereby when said members are moved to assume positions more or less partially obstructing said sound conduit, said recesses will be relatively positioned to centralize the passage of sound through the modulator structure and co-axially with respect to said conduit, a plate carried by the cabinet and having notches associated therewith, a plunger slidable in the cabinet, links pivotally connecting the inner ends of the plunger and jaws, the outer end of said plunger having spring actuated dogs for selectively engaging said notches, and aspring encircling the plunger for normally holding the links in a position to hold the jaws in their open positions. 1

In testimony whereof I aifix my signature.

CARL SCRABIC. 

